As processor packaging formats become larger and more complex, containing larger memory caches and being serviced by high speed high capacity busses, problems arise related to determining whether the processor is installed, and whether voltage may be applied, and, once applied, determining how best to regulate the voltage.
In prior art processors, a loop circuit may be used to detect power enable and, by derivation whether the processor is installed and fully seated. Because of the possibility of part damage due to currents from improperly seated parts and resulting poor electrical connections, it is crucial not to apply power unless a processor is fully installed. Such currents may cause the processor itself, the package contacts, and the cartridge to be damaged. Loop circuits have been used, as noted, to derive whether the processor is seated electrically based on the power enable signal as described. Such a derived approach has disadvantages in that the signal must be present for the system to power up. This signal is inappropriate to use as an indicator of a processor or terminator card being installed.
Another factor affecting processor operation is voltage regulation. A typical VRM associated with a processor circuit board has sense lines which allow for better regulation of supplied voltages by providing references to supplied voltages. Problems arise in that sense lines for regulating voltages on a typical circuit board to which a processor may be coupled may be connected to a voltage supply plane in close proximity to the VRM. Sensing voltages at the voltage supply plane of the circuit board may not accurately reflect the true state of voltages which most affect processor operation at a point which most accurately characterizes the voltage levels as they are seen by the processor. Further, voltage drops from circuits within the processor where the supply voltages are used to voltage supply planes where voltage levels are sensed may result in poor or inadequate voltage regulation where it is needed the most, e.g. to regulate voltage supply planes used in the processor.
It would be desirable therefore for an apparatus and method for providing an indication that a processor is properly seated and ready for the application of voltage. It would further be desirable for an apparatus and method which provides for improved regulation for internal processor voltages.